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Selenium

Uses

Our proprietary “Star-Rating” system was developed to help you easily understand the amount of scientific support behind each supplement in relation to a specific health condition. While there is no way to predict whether a vitamin, mineral, or herb will successfully treat or prevent associated health conditions, our unique ratings tell you how well these supplements are understood by the medical community, and whether studies have found them to be effective for other people.

For over a decade, our team has combed through thousands of research articles published in reputable journals. To help you make educated decisions, and to better understand controversial or confusing supplements, our medical experts have digested the science into these three easy-to-follow ratings. We hope this provides you with a helpful resource to make informed decisions towards your health and well-being.

1 StarFor an herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support.

This supplement has been used in connection with the following health conditions:

Used for

Why

2 Stars

Asthma

100 mcg daily

Asthma involves free-radical damage that selenium might protect against. In one trial, supplementing with sodium selenite (a form of selenium) improved symptoms in some patients.

People with low levels of selenium have a high risk of asthma.1, 2, 3, 4, 5 Asthma involves free-radical damage6 that selenium might protect against. In a small double-blind trial, supplementation with 100 mcg of sodium selenite (a form of selenium) per day for 14 weeks resulted in clinical improvement in six of eleven patients, compared with only one of ten in the placebo group.7 Most doctors recommend 200 mcg per day for adults (and proportionately less for children)—a much higher, though still safe, level.

2 Stars

Atherosclerosis

100 mcg daily

Some doctors recommend that people with atherosclerosis supplement with selenium, which has been shown in one study to help reduce the risk of death from heart disease.

In some studies, people who consumed more selenium in their diet had a lower risk of heart disease.8, 9 In one double-blind report, people who had already had one heart attack were given 100 mcg of selenium per day or placebo for six months.10 At the end of the trial, there were four deaths from heart disease in the placebo group but none in the selenium group; however, the number of people was too small for this difference to be statistically significant. Some doctors recommend that people with atherosclerosis supplement with 100–200 mcg of selenium per day.

2 Stars

Colon Cancer

200 mcg daily

Selenium appears to protect against a variety of cancers, including colon cancer.

Selenium has been reported to have diverse anticancer actions.12, 13 Selenium inhibits cancer in animals.14 Low soil levels of selenium, probably associated with low dietary intake, have been associated with increased cancer incidence in humans.15 Blood levels of selenium have been reported to be low in patients with a variety of cancers,16, 17, 18, 19, 20, 21, 22, 23 including colon cancer.24 In preliminary reports, people with the lowest blood levels of selenium had between 3.8 and 5.8 times the risk of dying from cancer compared with those who had the highest selenium levels.25, 26

The strongest evidence supporting the anticancer effects of selenium supplementation comes from a double-blind trial of 1,312 Americans with a history of skin cancer who were treated with 200 mcg of yeast-based selenium per day or placebo for 4.5 years, then followed for an additional two years.27 Although no decrease in skin cancers occurred, a dramatic 50% reduction in overall cancer deaths and a 37% reduction in total cancer incidence were observed. A statistically significant 58% decrease in cancers of the colon and rectum was reported.

2 Stars

Depression

100 mcg per day

Selenium deficiency may contribute to depression. Taking selenium can counteract this deficiency and improve depression symptoms.

Less than optimal intake of selenium may have adverse effects on psychological function, even in the absence of signs of frank selenium deficiency. In a preliminary trial of healthy young men, consumption of a high-selenium diet (226.5 mcg selenium per day) was associated with improved mood (i.e., decreased confusion, depression, anxiety, and uncertainty), compared to consumption of a low-selenium diet (62.6 mcg selenium per day.)28 In a double-blind trial, people who had a low selenium intake experienced greater improvement in depression symptoms after selenium supplementation (100 mcg per day) than did people with adequate selenium intake, suggesting that low-level selenium deficiency may contribute to depression.29

2 Stars

Dermatitis Herpetiformis

200 mcg daily

Supplementing with selenium and vitamin E has been shown to correct an antioxidant deficiency common in DH.

A deficiency in the selenium-containing antioxidant enzyme known as glutathione peroxidase has been reported in DH.30, 31 Preliminary32 and double-blind33 trials suggest that supplementation with 10 IU of vitamin E and 200 mcg of selenium per day for six to eight weeks corrected this deficiency but did not lead to symptom improvement in the double-blind trial.

2 Stars

Edema

230 mcg daily

People with lymphedema of the arm or head-and-neck region who were treated with selenium saw an improvement in quality of life and edema symptoms in one study.

In a preliminary study, individuals with lymphedema of the arm or head-and-neck region were treated with approximately 230 mcg of selenium per day, in the form of sodium selenite, for four to six weeks. A quality-of-life assessment showed an improvement of 59%, and the circumference of the edematous arm was reduced in 10 of 12 cases.34

2 Stars

Heart Attack

100 to 200 mcg daily

Some doctors recommend that people at risk for a heart attack supplement with selenium.

The relation between selenium and protection from heart attacks remains uncertain. Low blood levels of selenium have been reported in people immediately following a heart attack,35 suggesting that heart attacks may increase the need for selenium. However, other researchers claim that low selenium levels are present in people before they have a heart attack, suggesting that the lack of selenium might increase heart attack risk.36 One report found that low blood levels of selenium increased the risk of heart attack only in smokers,37 and another found the link only in former smokers.38 Yet others have found no link between low blood levels of selenium and heart attack risk whatsoever.39 In a double-blind trial, individuals who already had one heart attack were given 100 mcg of selenium per day or placebo for six months.40 At the end of the trial, there were four deaths from heart disease in the placebo group but none in the selenium group (although the numbers were too small for this difference to be statistically significant). In other controlled research, a similar group was given placebo or 500 mcg of selenium six hours or less after a heart attack followed by an ongoing regimen of 100 mcg of selenium plus 100 mg of coenzyme Q10 per day.41 One year later, six people had died from a repeat heart attack in the placebo group, compared with no heart attack deaths in the supplement group. Despite the lack of consistency in published research, some doctors recommend that people at risk for a heart attack supplement with selenium—most commonly 200 mcg per day.

2 Stars

HIV and AIDS Support

Take under medical supervision: 400 mcg daily

Supplementing with selenium may result in fewer infections, a healthier appetite, and other benefits.

Selenium deficiency is an independent factor associated with high mortality among HIV-positive people.42 HIV-positive people who took selenium supplements experienced fewer infections, better intestinal function, improved appetite, and improved heart function (which had been impaired by the disease) than those who did not take the supplements.43 The usual amount of selenium taken was 400 mcg per day.

Selenium deficiency has been found more often in people with HIV-related cardiomyopathy (heart abnormalities) than in those with HIV and normal heart function.44 People with HIV-related cardiomyopathy may benefit from selenium supplementation. In a small preliminary trial, people with AIDS and cardiomyopathy, 80% of whom were found to be deficient in selenium, were given 800 mcg of selenium per day for 15 days, followed by 400 mcg per day for eight days. Improvements in heart function were noted after selenium supplementation.45 People wishing to supplement with more than 200 mcg of selenium per day should be monitored by a doctor.

2 Stars

Immune Function

100 mcg daily with 20 mg zinc daily

Selenium supplements have been reported to help improve immune function in seniors.

Most,46, 47 but not all,48 double-blind studies have shown that elderly people have better immune function and reduced infection rates when taking a multiple vitamin-mineral formula. In one double-blind trial, supplements of 100 mcg per day of selenium and 20 mg per day of zinc, with or without additional vitamin C, vitamin E, and beta-carotene, reduced infections in elderly people, though vitamins without minerals had no effect.49 Burn victims have also experienced fewer infections after receiving trace mineral supplements in double-blind research.50 These studies suggest that trace minerals may be the most important micronutrients for enhancing immunity and preventing infections in the elderly.

2 Stars

Infection

100 mcg per day with 20 mg per day of zinc

Selenium supplements have been reported to help reduce infections in elderly people.

Most,51, 52 but not all,53 double-blind studies have shown that elderly people have better immune function and reduced infection rates when taking a multiple vitamin-mineral formula. In one double-blind trial, supplements of 100 mcg per day of selenium and 20 mg per day of zinc, with or without additional vitamin C, vitamin E, and beta-carotene, reduced infections in elderly people, though vitamins without minerals had no effect.54 Burn victims have also experienced fewer infections after receiving trace mineral supplements in double-blind research.55 These studies suggest that trace minerals may be the most important micronutrients for enhancing immunity and preventing infections in the elderly.

2 Stars

Lung Cancer

200 mcg daily

Selenium, reported to have diverse anticancer actions, has been shown in one study to reduce lung cancer incidence.

Selenium has been reported to have diverse anticancer actions.56, 57 Selenium inhibits cancer growth in animals.58 Low soil levels of selenium (probably associated with low dietary intake), have been associated with increased cancer incidence in humans.59 Blood levels of selenium have been reported to be low in patients with many cancers,60, 61, 62, 63, 64, 65, 66, 67 including lung cancer.68 In preliminary reports, people with the lowest blood levels of selenium had between 3.8 and 5.8 times the risk of dying from cancer compared with those who had the highest selenium levels.69, 70

The strongest evidence supporting the anticancer effects of selenium supplementation comes from a double-blind trial of 1,312 Americans with a history of skin cancer who were treated with 200 mcg of yeast-based selenium per day or a placebo for 4.5 years and then followed for an additional two years.71 Although no decrease in skin cancers occurred, a 50% reduction in overall cancer deaths and a 37% reduction in total cancer incidence was observed. A 46% decrease in lung cancer incidence and a 53% drop in deaths from lung cancer also occurred. These findings were all statistically significant.

2 Stars

Male Infertility

100 mcg daily

In a study of infertile men with reduced sperm motility, supplementing with selenium significantly increased sperm motility.

In a double-blind study of infertile men with reduced sperm motility, supplementation with selenium (100 mcg per day for three months) significantly increased sperm motility, but had no effect on sperm count. Eleven percent of 46 men receiving selenium achieved paternity, compared with none of 18 men receiving a placebo.72

2 Stars

Osgood-Schlatter Disease

150 mcg a day with 400 IU a day of vitamin E

Taking a combination of vitamin E and selenium may help the healing.

Based on the personal experience of a doctor who reported his findings,73 some physicians recommend vitamin E (400 IU per day) and selenium (50 mcg three times per day). One well-known, nutritionally oriented doctor reports anecdotally that he has had considerable success with this regimen and often sees results in two to six weeks.74

2 Stars

Pancreatic Insufficiency

600 mcg, taken under the supervision of a doctor

Taking antioxidant supplements, such as selenium, may lessen pain and prevent pancreatitis recurrences.

There are few controlled trials of antioxidant supplementation to patients with pancreatitis. One small controlled study of acute pancreatitis patients found that sodium selenite at a dose of 500 micrograms (mcg) daily resulted in decreased levels of a marker of free radical activity, and no patient deaths occurred.75 In a small double-blind trial including recurrent acute and chronic pancreatitis patients, supplements providing daily doses of 600 mcg selenium, 9,000 IU beta-carotene, 540 mg Vitamin C, 270 IU vitamin E, and 2,000 mg methionine significantly reduced pain, normalized several blood measures of antioxidant levels and free radical activity, and prevented acute recurrences of pancreatitis.76 These researchers later reported that continuing antioxidant treatment in these patients for up to five years or more significantly reduced the total number of days spent in hospital and resulted in 78% of patients becoming pain-free and 88% returning to work.77

2 Stars

Phenylketonuria

Adolescents and adults: 55 mcg daily; for infants and children: 15 to 40 mcg daily, according to age

Selenium deficiency may develop on the PKU diet, and supplementation may help correct this.

People with PKU may be deficient in several nutrients, due to the restricted diet which is low in protein and animal fat. Deficiencies of long-chain polyunsaturated fatty acids (LC-PUFAs),78, 79, 80selenium,81, 82, 83, 84vitamin B12,85 and vitamin K may develop on this diet.86

Selenium is important for normal antioxidant function. Research suggests that selenium deficiency and decreased antioxidant activity may contribute to the brain and nerve disorders associated with PKU.87 In two preliminary studies involving selenium-deficient people with PKU, supplementation with selenium in the form of sodium selenite corrected the deficiency,88 whereas supplementation with selenium in the form of selenomethionine did not.89

2 Stars

Prostate Cancer

200 mcg daily

Selenium has been reported to have diverse anticancer actions. Supplementing with this mineral may decrease your prostate cancer risk.

Selenium has been reported to have diverse anticancer actions.90, 91 Selenium inhibits cancer in animals.92 Low soil levels of selenium (probably associated with low dietary intake), have been associated with increased cancer incidence in humans.93 Blood levels of selenium have been reported to be low in patients with prostate cancer.94 In preliminary reports, people with the lowest blood levels of selenium had between 3.8 and 5.8 times the risk of dying from cancer compared with those who had the highest selenium levels.95, 96

The strongest evidence supporting the anticancer effects of selenium supplementation comes from a double-blind trial of 1,312 Americans with a history of skin cancer who were treated with 200 mcg of yeast-based selenium per day or placebo for 4.5 years and then followed for an additional two years.97 Although no decrease in skin cancers occurred, a dramatic 50% reduction in overall cancer deaths and a 37% reduction in total cancer incidence were observed. A statistically significant 63% decrease in prostate cancer incidence was reported.98 However, in a follow-up double-blind trial that included 35,533 healthy men, supplementing with 200 mcg per day of selenium for an average of 5.5 years had no effect on the incidence of prostate cancer.99 In another trial, 5,141 men were randomly assigned to receive a placebo or a daily supplement containing 100 mcg of selenium, 120 mg of vitamin C, 30 IU of vitamin E, 6 mg of beta-carotene, and 20 mg of zinc 20 for eight years. Among men with a normal PSA level at the start of the study, there was a statistically significant 48% reduction in the incidence of prostate cancer. Among men with an initially elevated PSA level, the supplemented group had an increased incidence of prostate cancer that was not statistically significant.100

2 Stars

Rheumatoid Arthritis

200 mcg daily

People with rheumatoid arthritis have been found to have lower selenium levels than healthy people. Supplementing with selenium may reduce pain and joint inflammation.

People with RA have been found to have lower selenium levels than healthy people.101, 102 One103 of two double-blind trials using at least 200 mcg of selenium per day for three to six months found that selenium supplementation led to a significant reduction in pain and joint inflammation in RA patients, but the other reported no beneficial effect.104 More controlled trials are needed to determine whether selenium reduces symptoms in people with RA.

1 Star

Abnormal Pap Smear

Refer to label instructions

Low levels of selenium have been observed in women with cervical dysplasia.

Low levels of selenium105 and low dietary intake of vitamin C106, 107 have been observed in women with cervical dysplasia.

1 Star

Age-Related Cognitive Decline

Refer to label instructions

In a preliminary trial of individuals with mild cognitive impairment and low blood levels of selenium, the improvement in measures of cognitive function was significantly greater in the group eating Brazil nuts than in the control group.

In a preliminary trial, elderly individuals with mild cognitive impairment and low blood levels of selenium consumed one Brazil nut per day (providing an estimated 289 mcg of selenium per day) or no Brazil nuts (control group) for 6 months. The improvement in measures of cognitive function was significantly greater in the group eating Brazil nuts than in the control group.108 Additional research is needed to determine whether taking selenium supplements or eating Brazil nuts would be beneficial for people with normal blood levels of selenium.

1 Star

Asthma (Vitamin C, Vitamin E)

Refer to label instructions

There is some evidence that a combination of antioxidants vitamin E, vitamin C, and selenium may help prevent asthma thought to be caused by air pollution.

There is some evidence that combinations of antioxidants such as vitamin E, vitamin C, and selenium may help improve symptoms of asthma throught to be caused by air pollution.109 In one double-blind study, 46 Dutch bicyclists were randomly assigned to receive a placebo or 100 mg of vitamin E and 500 mg of vitamin C daily for 15 weeks.110 Lung function was measured before and after each training session on 380 different occasions, and ambient ozone concentrations were measured during each training session. After analysis, researchers concluded that bicyclists with the vitamins C and E blunted the adverse effects of ozone on measures of lung function. In another double-blind study, 17 adults (18 to 39 years old) were randomly assigned to receive either 400 IU per day of vitamin E and 500 mg per day of vitamin C or a placebo for five weeks.111 Tests showing improved measures of lung function led researchers to conclude that supplementation with vitamins C and E inhibited the decline in pulmonary function induced in asthmatics by exposure to air pollutants. Also using a double-blind design, another study of 158 children with asthma living in Mexico City were randomly assigned to receive, a daily supplement containing 50 mg of vitamin E and 250 mg of vitamin C or a placebo.112 Tests results suggested that supplementing with vitamins C and E may reduce the adverse effect of ozone exposure on lung function of children with moderate to severe asthma.

1 Star

Cardiac Arrhythmia

Refer to label instructions

Supplementing with selenium may improve many arrhythmias.

Gross deficiency of dietary selenium may cause many heart problems, including arrhythmia. Based on this finding, one author has theorized that correction of low selenium status may improve many arrhythmias, even in the absence of overt deficiency symptoms.113 Controlled research is needed to evaluate this possibility.

1 Star

Cardiomyopathy and Keshan's Cardiomyopathy

Refer to label instructions

Supplementing with selenium can correct selenium deficiency, which is believed to be a cause of Keshan’s disease, a form of cardiomyopathy found in China.

Selenium deficiency has occasionally been reported as a cause of cardiomyopathy.114, 115 Selenium deficiency is the probable cause of Keshan’s disease, a form of cardiomyopathy found in China116, 117 but only rarely reported in the United States.118 Studies comparing populations in parts of the world other than mainland China have not supported a link between selenium deficiency and DCM,119, 120 except in Taiwan.121 Moreover, no clinical trials outside of China have explored the effects of supplementation with selenium for people with DCM, nor is there reason to believe that selenium supplementation would help most people outside of China and Taiwan suffering from cardiomyopathy.

1 Star

Childhood Diseases

Refer to label instructions

Supplementing with selenium, an antioxidant mineral, supports a healthy immune system and has been found to prevent viral infections.

Selenium is a mineral known to have antioxidant properties and to be involved in healthy immune system activity. Recent animal and human research suggests that selenium deficiency increases the risk of viral infection and that supplementation prevents viral infection.122, 123, 124, 125, 126 In a controlled trial, children with a specific viral infection (respiratory syncytial virus) who received a single supplement of 1 mg (1,000 mcg) of sodium selenite (a form of selenium) recovered more quickly than children who did not receive selenium.127 While it is possible that childhood exanthemous viral infections might similarly be more severe in selenium-deficient children and helped through supplementation, none of the current research involves these specific viruses.

1 Star

Down’s Syndrome

Refer to label instructions

People with Down’s syndrome may be deficient in selenium. A preliminary study found that antioxidant activity in the body improved when children with Down’s syndrome took selenium.

Blood levels of the antioxidant minerals selenium and zinc were normal in one study of people with Down’s syndrome,128 but others have found selenium129, 130 and zinc131, 132, 133 levels to be low. In some studies more than 60% of patients with Down’s syndrome had low zinc levels.134, 135 A preliminary study of selenium supplementation in children with Down’s syndrome found that the antioxidant activity in the body improved; however, the implications of this finding on the long-term health of these people is unclear.136 Zinc is critical for proper immune function, and in one preliminary study the majority of patients with Down’s syndrome examined had low zinc levels and low immune cell activity. Supplementation with zinc resulted in improved immune cell activity.137 In preliminary intervention trials, improved immune cell activity was associated with reduced rates of infection in Down’s syndrome patients given supplemental zinc in the amount of 1 mg per 2.2 pounds of body weight per day.138, 139 A controlled trial, however, did not find zinc, at 25 mg daily for children under 10 years of age and 50 mg for older children, to have these benefits.140 Zinc has other roles in the body; preliminary data have indicated that zinc supplementation, at 1 mg per 2.2 pounds of body weight per day, improved thyroid function in Down’s syndrome patients,141, 142, 143 and increased growth rate in children with Down’s syndrome.144

1 Star

Halitosis and Gum Disease

Spray a lotion containing 3.7% citronella in a slow-release formula every morning for six days per week

Selenium is often recommended by doctors to help prevent and treat periodontitis.

Nutritional supplements recommended by some doctors for prevention and treatment of periodontitis include vitamin C (people with periodontitis are often found to be deficient),145vitamin E, selenium, zinc, coenzyme Q10, and folic acid.146 Folic acid has also been shown to reduce the severity of gingivitis when taken as a mouthwash.147

1 Star

Hepatitis

100 mg per

In one trial, a combination of alpha lipoic acid, silymarin, and selenium led to significant improvements in liver function and overall health in people with hepatitis C.

A potent antioxidant combination may protect the liver from damage in people with hepatitis C, possibly decreasing the necessity for a liver transplant. In a preliminary trial,148 three people with liver cirrhosis and esophageal varices (dilated veins in the esophagus that can rupture and cause fatal bleeding) caused by hepatitis C received a combination of Alpha lipoic acid (300 mg twice daily), silymarin (from milk thistle; 300 mg three times daily), and selenium (selenomethionine; 200 mcg twice daily). After five to eight months of therapy that included other “supportive supplements,” such as vitamin C and B vitamins, all three people had significant improvements in their liver function and overall health. Larger clinical trials are needed to confirm these promising preliminary results.

1 Star

High Cholesterol

Refer to label instructions

A double-blind trial found that, in people with moderately elevated cholesterol levels, supplementing with selenium in the form of high-selenium yeast resulted in a small but statistically significant decrease in serum cholesterol.

In a double-blind trial, supplementation with selenium (100 or 200 mcg per day) in the form of high-selenium yeast for six months resulted in a small but statistically significant decrease in serum cholesterol levels, compared with a placebo, in people with moderately elevated cholesterol levels. Selenium in the amount of 300 mcg per day was resulted in a smaller decrease in cholesterol levels that was not statistically significant.149 High-selenium yeast contains one or more unique selenium-containing compounds that are not present in other selenium supplements. Additional research is therefore needed to determine whether other forms of selenium also lower cholesterol levels.

1 Star

Hypothyroidism

Refer to label instructions

Selenium plays a role in thyroid hormone metabolism. People who are deficient in selenium may benefit from supplementation.

Selenium plays a role in thyroid hormone metabolism. Severe selenium deficiency has been implicated as a possible cause of goiter.150 Two months of selenium supplementation in people who were deficient in both selenium and iodine was shown to induce a dramatic fall of the already impaired thyroid function in clinically hypothyroid subjects.151 Researchers have suggested that people who are deficient in both selenium and iodine should not take selenium supplements without first receiving iodine or thyroid hormone supplementation.152 There is no research demonstrating that selenium supplementation helps people with hypothyroidism who are not selenium-deficient.

1 Star

Liver Cirrhosis

Refer to label instructions

People with liver cirrhosis often have low selenium levels and a greater need for antioxidants. In one study, selenium improved liver function in people with alcoholic cirrhosis.

Selenium levels have been found to be low in people with liver cirrhosis153 and the need for antioxidants has been found to be increased.154 A small, preliminary trial suggested that 100 mcg per day of selenium may improve liver function in people with alcoholic cirrhosis.155 Larger, double-blind trials of selenium in people with liver cirrhosis are needed.

1 Star

Macular Degeneration

Refer to label instructions

Sunlight triggers oxidative damage in the eye, which can cause macular degeneration. Selenium protects against oxidative damage and may reduce macular degeneration risk.

Sunlight triggers oxidative damage in the eye, which in turn can cause macular degeneration.156 Animals given antioxidants—which protect against oxidative damage—have a lower risk of this vision problem.157 People with high blood levels of antioxidants also have a lower risk.158 Those with the highest levels (top 20th percentile) of the antioxidants selenium, vitamin C, and vitamin E may have a 70% lower risk of developing macular degeneration, compared with people with the lowest levels of these nutrients (bottom 20th percentile).159 People who eat fruits and vegetables high in beta-carotene, another antioxidant, are also at low risk.160 Some doctors recommend antioxidant supplements to reduce the risk of macular degeneration; reasonable adult levels include 200 mcg of selenium, 1,000 mg of vitamin C, 400 IU of vitamin E, and 25,000 IU of natural beta-carotene per day. However, a preliminary study found no association between age-related macular degeneration and intake of antioxidants, either from the diet, from supplements, or from both combined.161 Moreover, in a double-blind study of male cigarette smokers, supplementing with vitamin E (50 IU per day), synthetic beta-carotene (about 33,000 IU per day), or both did not reduce the incidence of age-related macular degeneration.162

1 Star

Pre- and Post-Surgery Health

Refer to label instructions

Selenium has an important role in immune function and infection prevention, and supplementing with it may correct a postoperative selenium deficiency.

Selenium is a mineral nutrient with an important role in immune function and infection prevention,163, 164, 165 and selenium deficiency has been reported in patients after intestinal surgery.166 A controlled trial of critically ill patients, including some with recent major surgery, found that those receiving daily intravenous selenium injections for three weeks showed less biochemical signs of body stress compared with unsupplemented patients. The amount used in this trial was 500 mcg twice daily for the first week, 500 mcg once daily for the second week, and 100 mcg three times daily for the third week.167

A combination of the antioxidants selenium, vitamin A, vitamin C, and vitamin E has been shown to improve diabetic retinopathy.

Because oxidation damage is believed to play a role in the development of diabetic eye damage (retinopathy), antioxidant nutrients might be protective. One doctor has administered a daily regimen of 500 mcg selenium, 800 IU vitamin E, 10,000 IU vitamin A, and 1,000 mg vitamin C for several years to 20 people with diabetic eye damage (retinopathy). During that time, 19 of the 20 people showed either improvement or no progression of their retinopathy.168 People who wish to supplement with more than 250 mcg of selenium per day should consult a healthcare practitioner.

Because oxidation damage is believed to play a role in the development of diabetic eye damage (retinopathy), antioxidant nutrients might be protective. One doctor has administered a daily regimen of 500 mcg selenium, 800 IU vitamin E, 10,000 IU vitamin A, and 1,000 mg vitamin C for several years to 20 people with diabetic eye damage (retinopathy). During that time, 19 of the 20 people showed either improvement or no progression of their retinopathy.169 People who wish to supplement with more than 250 mcg of selenium per day should consult a healthcare practitioner.

How It Works

How to Use It

While the Recommended Dietary Allowance for most adults is 55 mcg per day, an adult intake of 100–200 mcg of selenium per day is recommended by many doctors.

Where to Find It

Brazil nuts are the best source of selenium. Yeast, whole grains, and seafood are also good sources. Animal studies have found that selenium from yeast is better absorbed than selenium in the form of selenite.170

Possible Deficiencies

While most people probably don’t take in enough selenium, gross deficiencies are rare in Western countries. Soils in some areas are selenium-deficient and people who eat foods grown primarily on selenium-poor soils are at risk for deficiency. People with AIDS have been reported to be depleted in selenium.171 Similarly, limited research has reported an association between heart disease and depleted levels of selenium.172 People who are deficient in selenium have an increased risk of developing certain types of rheumatoid arthritis.173

Interactions with Medicines

Replenish Depleted Nutrients

One controlled study showed that taking clozapine can decrease blood levels of selenium, a mineral with antioxidant activity.188 While more research is needed to determine whether people taking clozapine might require selenium supplementation, until more information is available, some health practitioners recommend supplementation.

Reduce Side Effects

In one human study, administration of 4,000 mcg per day of a selenium product, Seleno-Kappacarrageenan, reduced the kidney damage and white blood cell–lowering effects of the chemotherapy drug cisplatin.174 The amount of selenium used in this study is potentially toxic and should only be used under the supervision of a doctor. In another study, patients being treated with cisplatin and cyclophosphamide for ovarian cancer were given a multivitamin preparation, with or without 200 mcg of selenium per day. Compared with the group not receiving selenium, those receiving selenium had a smaller reduction in white blood cell count and fewer chemotherapy side effects such as nausea, hair loss, weakness, and loss of appetite.175

In one human study, administration of 4,000 mcg per day of a selenium product, Seleno-Kappacarrageenan, reduced the kidney damage and white blood cell–lowering effects of the chemotherapy drug cisplatin.176 The amount of selenium used in this study is potentially toxic and should only be used under the supervision of a doctor. In another study, patients being treated with cisplatin and cyclophosphamide for ovarian cancer were given a multivitamin preparation, with or without 200 mcg of selenium per day. Compared with the group not receiving selenium, those receiving selenium had a smaller reduction in white blood cell count and fewer chemotherapy side effects such as nausea, hair loss, weakness, and loss of appetite.177

In one human study, administration of 4,000 mcg per day of a selenium product, Seleno-Kappacarrageenan, reduced the kidney damage and white blood cell–lowering effects of the chemotherapy drug cisplatin.178 The amount of selenium used in this study is potentially toxic and should only be used under the supervision of a doctor. In another study, patients being treated with cisplatin and cyclophosphamide for ovarian cancer were given a multivitamin preparation, with or without 200 mcg of selenium per day. Compared with the group not receiving selenium, those receiving selenium had a smaller reduction in white blood cell count and fewer chemotherapy side effects such as nausea, hair loss, weakness, and loss of appetite.179

In one human study, administration of 4,000 mcg per day of a selenium product, Seleno-Kappacarrageenan, reduced the kidney damage and white blood cell–lowering effects of the chemotherapy drug cisplatin.180 The amount of selenium used in this study is potentially toxic and should only be used under the supervision of a doctor. In another study, patients being treated with cisplatin and cyclophosphamide for ovarian cancer were given a multivitamin preparation, with or without 200 mcg of selenium per day. Compared with the group not receiving selenium, those receiving selenium had a smaller reduction in white blood cell count and fewer chemotherapy side effects such as nausea, hair loss, weakness, and loss of appetite.181

In one human study, administration of 4,000 mcg per day of a selenium product, Seleno-Kappacarrageenan, reduced the kidney damage and white blood cell–lowering effects of the chemotherapy drug cisplatin.182 The amount of selenium used in this study is potentially toxic and should only be used under the supervision of a doctor. In another study, patients being treated with cisplatin and cyclophosphamide for ovarian cancer were given a multivitamin preparation, with or without 200 mcg of selenium per day. Compared with the group not receiving selenium, those receiving selenium had a smaller reduction in white blood cell count and fewer chemotherapy side effects such as nausea, hair loss, weakness, and loss of appetite.183

In one human study, administration of 4,000 mcg per day of a selenium product, Seleno-Kappacarrageenan, reduced the kidney damage and white blood cell–lowering effects of cisplatin.184 The amount of selenium used in this study is potentially toxic and should only be used under the supervision of a doctor. In another study, patients being treated with cisplatin and cyclophosphamide for ovarian cancer were given a multivitamin preparation, with or without 200 mcg of selenium per day. Compared with the group not receiving selenium, those receiving selenium had a smaller reduction in white blood cell count and fewer chemotherapy side effects such as nausea, hair loss, weakness, and loss of appetite.185

In one human study, administration of 4,000 mcg per day of a selenium product, Seleno-Kappacarrageenan, reduced the kidney damage and white blood cell–lowering effects of the chemotherapy drug cisplatin.186 The amount of selenium used in this study is potentially toxic and should only be used under the supervision of a doctor. In another study, patients being treated with cisplatin and cyclophosphamide for ovarian cancer were given a multivitamin preparation, with or without 200 mcg of selenium per day. Compared with the group not receiving selenium, those receiving selenium had a smaller reduction in white blood cell count and fewer chemotherapy side effects such as nausea, hair loss, weakness, and loss of appetite.187

Patients being treated with cyclophosphamide and cisplatin for ovarian cancer were given a multivitamin preparation, with or without 200 mcg of selenium per day. Compared with the group not receiving selenium, those receiving selenium had a smaller reduction in white blood cell count and fewer chemotherapy side effects such as nausea, hair loss, weakness, and loss of appetite.189

In one human study, administration of 4,000 mcg per day of a selenium product, Seleno-Kappacarrageenan, reduced the kidney damage and white blood cell–lowering effects of the chemotherapy drug cisplatin.190 The amount of selenium used in this study is potentially toxic and should only be used under the supervision of a doctor. In another study, patients being treated with cisplatin and cyclophosphamide for ovarian cancer were given a multivitamin preparation, with or without 200 mcg of selenium per day. Compared with the group not receiving selenium, those receiving selenium had a smaller reduction in white blood cell count and fewer chemotherapy side effects such as nausea, hair loss, weakness, and loss of appetite.191

Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.194 However, most scientific research does not support this supposition.

A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.195Vitamin C appears to increase the effectiveness of chemotherapy in animals196 and with human breast cancer cells in test tube research.197 In a double-blind study, Japanese researchers found that the combination of vitamin E, vitamin C, and N-acetyl cysteine (NAC)—all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.198

A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but it clearly shows that antioxidants need not be avoided for fear that the actions of chemotherapy are interfered with.199 Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.

A new formulation of selenium (Seleno-Kappacarrageenan) was found to reduce kidney damage and white blood cell–lowering effects of cisplatin in one human study. However, the level used in this study (4,000 mcg per day) is potentially toxic and should only be used under the supervision of a doctor.200

In one human study, administration of 4,000 mcg per day of a selenium product, Seleno-Kappacarrageenan, reduced the kidney damage and white blood cell–lowering effects of the chemotherapy drug cisplatin.201 The amount of selenium used in this study is potentially toxic and should only be used under the supervision of a doctor. In another study, patients being treated with cisplatin and cyclophosphamide for ovarian cancer were given a multivitamin preparation, with or without 200 mcg of selenium per day. Compared with the group not receiving selenium, those receiving selenium had a smaller reduction in white blood cell count and fewer chemotherapy side effects such as nausea, hair loss, weakness, and loss of appetite.202

In one human study, administration of 4,000 mcg per day of a selenium product, Seleno-Kappacarrageenan, reduced the kidney damage and white blood cell–lowering effects of the chemotherapy drug cisplatin.203 The amount of selenium used in this study is potentially toxic and should only be used under the supervision of a doctor. In another study, patients being treated with cisplatin and cyclophosphamide for ovarian cancer were given a multivitamin preparation, with or without 200 mcg of selenium per day. Compared with the group not receiving selenium, those receiving selenium had a smaller reduction in white blood cell count and fewer chemotherapy side effects such as nausea, hair loss, weakness, and loss of appetite.204

In one human study, administration of 4,000 mcg per day of a selenium product, Seleno-Kappacarrageenan, reduced the kidney damage and white blood cell–lowering effects of the chemotherapy drug cisplatin.205 The amount of selenium used in this study is potentially toxic and should only be used under the supervision of a doctor. In another study, patients being treated with cisplatin and cyclophosphamide for ovarian cancer were given a multivitamin preparation, with or without 200 mcg of selenium per day. Compared with the group not receiving selenium, those receiving selenium had a smaller reduction in white blood cell count and fewer chemotherapy side effects such as nausea, hair loss, weakness, and loss of appetite.206

In one human study, administration of 4,000 mcg per day of a selenium product, Seleno-Kappacarrageenan, reduced the kidney damage and white blood cell–lowering effects of the chemotherapy drug cisplatin.207 The amount of selenium used in this study is potentially toxic and should only be used under the supervision of a doctor. In another study, patients being treated with cisplatin and cyclophosphamide for ovarian cancer were given a multivitamin preparation, with or without 200 mcg of selenium per day. Compared with the group not receiving selenium, those receiving selenium had a smaller reduction in white blood cell count and fewer chemotherapy side effects such as nausea, hair loss, weakness, and loss of appetite.208

Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.209 However, most scientific research does not support this supposition.

A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.210Vitamin C appears to increase the effectiveness of chemotherapy in animals211 and with human breast cancer cells in test tube research.212 In a double-blind study, Japanese researchers found that the combination of vitamin E, vitamin C, and N-acetyl cysteine (NAC)—all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.213

A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but the article strongly suggests that antioxidants need not be avoided for fear that the actions of chemotherapy would be interfered with.214

A new formulation of selenium (Seleno-Kappacarrageenan) was found to reduce kidney damage and white blood cell–lowering effects of cisplatin in one human study. However, the level used in this study (4,000 mcg per day) is potentially toxic and should only be used under the supervision of a doctor.215

In one human study, administration of 4,000 mcg per day of a selenium product, Seleno-Kappacarrageenan, reduced the kidney damage and white blood cell–lowering effects of the chemotherapy drug cisplatin.216 The amount of selenium used in this study is potentially toxic and should only be used under the supervision of a doctor. In another study, patients being treated with cisplatin and cyclophosphamide for ovarian cancer were given a multivitamin preparation, with or without 200 mcg of selenium per day. Compared with the group not receiving selenium, those receiving selenium had a smaller reduction in white blood cell count and fewer chemotherapy side effects such as nausea, hair loss, weakness, and loss of appetite.217

In one human study, administration of 4,000 mcg per day of a selenium product, Seleno-Kappacarrageenan, reduced the kidney damage and white blood cell–lowering effects of the chemotherapy drug cisplatin.218 The amount of selenium used in this study is potentially toxic and should only be used under the supervision of a doctor. In another study, patients being treated with cisplatin and cyclophosphamide for ovarian cancer were given a multivitamin preparation, with or without 200 mcg of selenium per day. Compared with the group not receiving selenium, those receiving selenium had a smaller reduction in white blood cell count and fewer chemotherapy side effects such as nausea, hair loss, weakness, and loss of appetite.219

In one human study, administration of 4,000 mcg per day of a selenium product, Seleno-Kappacarrageenan, reduced the kidney damage and white blood cell–lowering effects of the chemotherapy drug cisplatin.220 The amount of selenium used in this study is potentially toxic and should only be used under the supervision of a doctor. In another study, patients being treated with cisplatin and cyclophosphamide for ovarian cancer were given a multivitamin preparation, with or without 200 mcg of selenium per day. Compared with the group not receiving selenium, those receiving selenium had a smaller reduction in white blood cell count and fewer chemotherapy side effects such as nausea, hair loss, weakness, and loss of appetite.221

In one human study, administration of 4,000 mcg per day of a selenium product, Seleno-Kappacarrageenan, reduced the kidney damage and white blood cell–lowering effects of the chemotherapy drug cisplatin.222 The amount of selenium used in this study is potentially toxic and should only be used under the supervision of a doctor. In another study, patients being treated with cisplatin and cyclophosphamide for ovarian cancer were given a multivitamin preparation, with or without 200 mcg of selenium per day. Compared with the group not receiving selenium, those receiving selenium had a smaller reduction in white blood cell count and fewer chemotherapy side effects such as nausea, hair loss, weakness, and loss of appetite.223

In one human study, administration of 4,000 mcg per day of a selenium product, Seleno-Kappacarrageenan, reduced the kidney damage and white blood cell–lowering effects of the chemotherapy drug cisplatin.224 The amount of selenium used in this study is potentially toxic and should only be used under the supervision of a doctor. In another study, patients being treated with cisplatin and cyclophosphamide for ovarian cancer were given a multivitamin preparation, with or without 200 mcg of selenium per day. Compared with the group not receiving selenium, those receiving selenium had a smaller reduction in white blood cell count and fewer chemotherapy side effects such as nausea, hair loss, weakness, and loss of appetite.225

In one human study, administration of 4,000 mcg per day of a selenium product, Seleno-Kappacarrageenan, reduced the kidney damage and white blood cell–lowering effects of the chemotherapy drug cisplatin.226 The amount of selenium used in this study is potentially toxic and should only be used under the supervision of a doctor. In another study, patients being treated with cisplatin and cyclophosphamide for ovarian cancer were given a multivitamin preparation, with or without 200 mcg of selenium per day. Compared with the group not receiving selenium, those receiving selenium had a smaller reduction in white blood cell count and fewer chemotherapy side effects such as nausea, hair loss, weakness, and loss of appetite.227

In one human study, administration of 4,000 mcg per day of a selenium product, Seleno-Kappacarrageenan, reduced the kidney damage and white blood cell–lowering effects of the chemotherapy drug cisplatin.228 The amount of selenium used in this study is potentially toxic and should only be used under the supervision of a doctor. In another study, patients being treated with cisplatin and cyclophosphamide for ovarian cancer were given a multivitamin preparation, with or without 200 mcg of selenium per day. Compared with the group not receiving selenium, those receiving selenium had a smaller reduction in white blood cell count and fewer chemotherapy side effects such as nausea, hair loss, weakness, and loss of appetite.229

Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.230 However, most scientific research does not support this supposition.

A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.231Vitamin C appears to increase the effectiveness of chemotherapy in animals232 and with human breast cancer cells in test tube research.233 In a double-blind study, Japanese researchers found that the combination of vitamin E, vitamin C, and N-acetyl cysteine (NAC)—all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.234

A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but it clearly shows that antioxidants need not be avoided for fear that the actions of chemotherapy are interfered with.235 Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.

A new formulation of selenium (Seleno-Kappacarrageenan) was found to reduce kidney damage and white blood cell–lowering effects of cisplatin in one human study. However, the level used in this study (4,000 mcg per day) is potentially toxic and should only be used under the supervision of a doctor.236

Glutathione, the main antioxidant found within cells, is frequently depleted in individuals on chemotherapy and/or radiation. Preliminary studies have found that intravenously injected glutathione may decrease some of the adverse effects of chemotherapy and radiation, such as diarrhea.237

In one human study, administration of 4,000 mcg per day of a selenium product, Seleno-Kappacarrageenan, reduced the kidney damage and white blood cell–lowering effects of the chemotherapy drug cisplatin.240 The amount of selenium used in this study is potentially toxic and should only be used under the supervision of a doctor. In another study, patients being treated with cisplatin and cyclophosphamide for ovarian cancer were given a multivitamin preparation, with or without 200 mcg of selenium per day. Compared with the group not receiving selenium, those receiving selenium had a smaller reduction in white blood cell count and fewer chemotherapy side effects such as nausea, hair loss, weakness, and loss of appetite.241

In one human study, administration of 4,000 mcg per day of a selenium product, Seleno-Kappacarrageenan, reduced the kidney damage and white blood cell–lowering effects of the chemotherapy drug cisplatin.246 The amount of selenium used in this study is potentially toxic and should only be used under the supervision of a doctor. In another study, patients being treated with cisplatin and cyclophosphamide for ovarian cancer were given a multivitamin preparation, with or without 200 mcg of selenium per day. Compared with the group not receiving selenium, those receiving selenium had a smaller reduction in white blood cell count and fewer chemotherapy side effects such as nausea, hair loss, weakness, and loss of appetite.247

In one human study, administration of 4,000 mcg per day of a selenium product, Seleno-Kappacarrageenan, reduced the kidney damage and white blood cell–lowering effects of cisplatin.248 The amount of selenium used in this study is potentially toxic and should only be used under the supervision of a doctor. In another study, patients being treated with cisplatin and cyclophosphamide for ovarian cancer were given a multivitamin preparation, with or without 200 mcg of selenium per day. Compared with the group not receiving selenium, those receiving selenium had a smaller reduction in white blood cell count and fewer chemotherapy side effects such as nausea, hair loss, weakness, and loss of appetite.249

In one human study, administration of 4,000 mcg per day of a selenium product, Seleno-Kappacarrageenan, reduced the kidney damage and white blood cell–lowering effects of the chemotherapy drug cisplatin.250 The amount of selenium used in this study is potentially toxic and should only be used under the supervision of a doctor. In another study, patients being treated with cisplatin and cyclophosphamide for ovarian cancer were given a multivitamin preparation, with or without 200 mcg of selenium per day. Compared with the group not receiving selenium, those receiving selenium had a smaller reduction in white blood cell count and fewer chemotherapy side effects such as nausea, hair loss, weakness, and loss of appetite.251

In one human study, administration of 4,000 mcg per day of a selenium product, Seleno-Kappacarrageenan, reduced the kidney damage and white blood cell–lowering effects of the chemotherapy drug cisplatin.252 The amount of selenium used in this study is potentially toxic and should only be used under the supervision of a doctor. In another study, patients being treated with cisplatin and cyclophosphamide for ovarian cancer were given a multivitamin preparation, with or without 200 mcg of selenium per day. Compared with the group not receiving selenium, those receiving selenium had a smaller reduction in white blood cell count and fewer chemotherapy side effects such as nausea, hair loss, weakness, and loss of appetite.253

In one human study, administration of 4,000 mcg per day of a selenium product, Seleno-Kappacarrageenan, reduced the kidney damage and white blood cell–lowering effects of the chemotherapy drug cisplatin.254 The amount of selenium used in this study is potentially toxic and should only be used under the supervision of a doctor. In another study, patients being treated with cisplatin and cyclophosphamide for ovarian cancer were given a multivitamin preparation, with or without 200 mcg of selenium per day. Compared with the group not receiving selenium, those receiving selenium had a smaller reduction in white blood cell count and fewer chemotherapy side effects such as nausea, hair loss, weakness, and loss of appetite.255

Potential Negative Interaction

Explanation Required

On the basis of the biochemical actions of valproic acid, it has been suggested that people taking valproic acid should make sure they have adequate intakes of vitamin E and selenium.258 The importance of supplementation with either nutrient has not yet been tested, however.

The Drug-Nutrient Interactions table may not include every possible interaction. Taking medicines with meals, on an empty stomach, or with alcohol may influence their effects. For details, refer to the manufacturers’ package information as these are not covered in this table. If you take medications, always discuss the potential risks and benefits of adding a supplement with your doctor or pharmacist.

Side Effects

Side Effects

Selenium is safe at the level people typically supplement (100–200 mcg); however, taking more than 900 mcg of selenium per day has been reported to cause adverse effects in some people.259 Selenium toxicity can result in loss of fingernails, skin rash, and changes in the nervous system. In the presence of iodine-deficiency-induced goiter, selenium supplementation has been reported to exacerbate low thyroid function.260 Although most research suggests that
selenium prevents cancer, one study found an increased risk of a type of skin
cancer (squamous cell carcinoma) in people taking selenium
supplements.261 The National Academy of Sciences recommends that selenium intake not exceed 400 mcg per day, unless the higher intake is monitored by a healthcare professional.262 In a double-blind study of people who took 200 mcg of selenium per day for several years to prevent recurrences of skin cancer, the incidence of diabetes was higher in people who received selenium (9.7%) than in those who received a placebo (6.5%).263 While this difference was statistically significant, this finding should be considered preliminary, since the study was not originally designed to test whether selenium influences the risk of developing diabetes.

237. De Maria D, Falchi AM, Venturino P. Adjuvant radiotherapy of the pelvis with or without reduced glutathione: a randomized trial in patients operated on for endometrial cancer. Tumori 1992;78:374-6.

The information presented in Aisle7 is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires June 2016.

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NOTICE: This health information was not created by the University of Michigan Health System (UMHS) and may not necessarily reflect specific UMHS practices. For medical advice relating to your personal condition, please consult your doctor. Complete disclaimer